SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e4d1bc45c31e0aee9dd063b169f9396084967e2e4184e7d15ff11b01245835e' 
  AND token = 'R6FxfqNJvMIzkwf5qYUVWBF7vHrik4ZSTKgWvpaLK8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}